1. Technical Field
The present invention relates generally to temperature sensing devices and methods and more specifically to a method of obtaining a digital temperature measurement from an integrated circuit.
2. Description of the Related Art
There are many applications in which the ability to measure the temperature of an integrated circuit is helpful. For example, circuits that generate high power outputs, such as power amplifier circuits, may easily become overheated under high power conditions. Similarly, many modern microprocessors produce significant amounts of thermal energy when operating at today's high clock speeds. In such instances, it is critical to avoid overheating of components.
For example, high-speed microcomputers, and in particular mobile computers such as notebook or laptop computers, are designed to lower the clock rate of the microprocessor when the microprocessor begins to exhibit an overly high temperature.
Existing integrated circuit (IC) temperature sensors tend to be highly complex, and those having digital output are even more complex. Examples of analog IC temperature sensors, which illustrate a variety of complex circuit topologies, include U.S. Pat. Nos. 4,021,722; 4,047,435; 6,188,270; 6,489,831; 6,783,274; 6,799,889; and 5,980,106. One example of an existing digital-output sensor design is provided in BAKKER, Anton, et al. Micropower CMOS Temperature Sensor with Digital Output. IEEE j. solid-state circuits. July 1996, vol. 31, no. 7, pp. 933–937. The BAKKER design utilizes a ΣΔ analog-to-digital converter, which imposes a considerable degree of complexity on an already-complex analog sensor design.
Reducing the complexity of temperature sensor circuits is important, as greater complexity often results in physically larger circuits. In large-scale, high power integrated circuits, where multiple temperature sensors are typically needed, these large and complex circuits are expensive and inefficient to produce.
What is needed, therefore, is a simple method of acquiring a digital indication of the temperature of an integrated circuit. The present invention provides a solution to these and other problems, and offers other advantages over previous solutions.